NFS Services Administrator's Guide

Configuring and Administering NFS
Preparing for NFS Configuration
Chapter 224
— Each user has the same user ID on all machines where that user
has an account.
— No two users anywhere on the network have the same user ID.
— Each group has the same group ID on all machines where that
group exists.
— No two groups on the network have the same group ID.
When users request NFS access to remote files, their user IDs and group
IDs are used to check file ownership and permissions, just as they are
locally.
If a user has one user ID on an NFS client and a different user ID on an
NFS server, the server will not grant the user access to his or her files on
the server, because it thinks the files belong to someone else.
If a user on one machine has the same user ID as a user on another
machine, one user may gain access to the other user’s files.
For information on the /etc/passwd and /etc/group files, type man 4
passwd or man 4 group at the HP-UX prompt.
If you are using NIS or NIS+, the /etc/passwd and /etc/group files are
managed by a master server, and all other machines on the network
request user and group information from the servers. With NIS or NIS+,
it is unnecessary to set user IDs and group IDs on each machine. For
instructions on configuring NIS, see “Configuring and Administering
NIS” on page 145. For instructions on configuring NIS+, see “Configuring
and Administering NIS+” on page 199.
To Ensure that No User is a Member of Too Many
Groups
1. If you are not running NIS or NIS+, issue the following command for
each user on your system:
/usr/bin/grep -c username /etc/group
This command returns the number of occurrences of username in the
/etc/group file.
If you are using NIS to manage your group database, issue the
following command for each user in your domain:
/usr/bin/ypcat -k group | /usr/bin/grep -c username